The Experts below are selected from a list of 84228 Experts worldwide ranked by ideXlab platform
Fenzhuo Guo - One of the best experts on this subject based on the ideXlab platform.
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spin image of an atomic vapor cell with a resolution smaller than the diffusion crosstalk free distance
Journal of Applied Physics, 2019Co-Authors: Haifeng Dong, Jingling Chen, Chen Liu, Nan Zhao, Fenzhuo GuoAbstract:The diffusion crosstalk free distance is an important parameter for spin images in atomic vapor cells and is also regarded as a Limit on the spatial resolution. However, by modulating the pumping light both spatially and temporally using a digital micromirror device, a spin image of a vapor cell has been obtained with a distinguishable stripe width of 13.7 μm, which is much smaller than the corresponding diffusion crosstalk free distance of ∼138 μm. The Fundamental Limit on the spatial resolution as determined by diffusion and the uncertainty principle is analyzed.The diffusion crosstalk free distance is an important parameter for spin images in atomic vapor cells and is also regarded as a Limit on the spatial resolution. However, by modulating the pumping light both spatially and temporally using a digital micromirror device, a spin image of a vapor cell has been obtained with a distinguishable stripe width of 13.7 μm, which is much smaller than the corresponding diffusion crosstalk free distance of ∼138 μm. The Fundamental Limit on the spatial resolution as determined by diffusion and the uncertainty principle is analyzed.
Byonghyo Shim - One of the best experts on this subject based on the ideXlab platform.
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exact recovery of sparse signals using orthogonal matching pursuit how many iterations do we need
IEEE Transactions on Signal Processing, 2016Co-Authors: Jian Wang, Byonghyo ShimAbstract:Orthogonal matching pursuit (OMP) is a greedy algorithm widely used for the recovery of sparse signals from compressed measurements. In this paper, we analyze the number of iterations required for the OMP algorithm to perform exact recovery of sparse signals. Our analysis shows that OMP can accurately recover all $K$ -sparse signals within $\lceil 2.8 \; K \rceil$ iterations when the measurement matrix satisfies a restricted isometry property (RIP). Our result improves upon the recent result of Zhang and also bridges the gap between Zhang's result and the Fundamental Limit of OMP at which exact recovery of $K$ -sparse signals cannot be uniformly guaranteed.
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on the recovery Limit of sparse signals using orthogonal matching pursuit
IEEE Transactions on Signal Processing, 2012Co-Authors: Jian Wang, Byonghyo ShimAbstract:Orthogonal matching pursuit (OMP) is a greedy search algorithm popularly being used for the recovery of compressive sensed sparse signals. In this correspondence, we show that if the isometry constant δK+1 of the sensing matrix Φ satisfies δK+1 <; 1/(1/√K+1) then the OMP algorithm can perfectly recover K-sparse signals from the compressed measurements y=Φx. Our bound offers a substantial improvement over the recent result of Davenport and Wakin and also closes gap between the recovery bound and Fundamental Limit over which the perfect recovery of the OMP cannot be guaranteed.
Shidong Zhou - One of the best experts on this subject based on the ideXlab platform.
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spectrum and energy efficient beamspace mimo noma for millimeter wave communications using lens antenna array
arXiv: Information Theory, 2017Co-Authors: Bichai Wang, Linglong Dai, Zhaocheng Wang, Shidong ZhouAbstract:The recent concept of beamspace multiple input multiple output (MIMO) can significantly reduce the number of required radio-frequency (RF) chains in millimeter-wave (mmWave) massive MIMO systems without obvious performance loss. However, the Fundamental Limit of existing beamspace MIMO is that, the number of supported users cannot be larger than the number of RF chains at the same time-frequency resources. To break this Fundamental Limit, in this paper we propose a new spectrum and energy efficient mmWave transmission scheme that integrates the concept of non-orthogonal multiple access (NOMA) with beamspace MIMO, i.e., beamspace MIMO-NOMA. By using NOMA in beamspace MIMO systems, the number of supported users can be larger than the number of RF chains at the same time-frequency resources. Particularly, the achievable sum rate of the proposed beamspace MIMO-NOMA in a typical mmWave channel model is analyzed, which shows an obvious performance gain compared with the existing beamspace MIMO. Then, a precoding scheme based on the principle of zero-forcing (ZF) is designed to reduce the inter-beam interferences in the beamspace MIMO-NOMA system. Furthermore, to maximize the achievable sum rate, a dynamic power allocation is proposed by solving the joint power optimization problem, which not only includes the intra-beam power optimization, but also considers the inter-beam power optimization. Finally, an iterative optimization algorithm with low complexity is developed to realize the dynamic power allocation. Simulation results show that the proposed beamspace MIMO-NOMA can achieve higher spectrum and energy efficiency compared with existing beamspace MIMO.
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spectrum and energy efficient beamspace mimo noma for millimeter wave communications using lens antenna array
IEEE Journal on Selected Areas in Communications, 2017Co-Authors: Bichai Wang, Linglong Dai, Zhaocheng Wang, Shidong ZhouAbstract:The recent concept of beamspace multiple input multiple output (MIMO) can significantly reduce the number of required radio frequency (RF) chains in millimeter-wave (mmWave) massive MIMO systems without obvious performance loss. However, the Fundamental Limit of existing beamspace MIMO is that the number of supported users cannot be larger than the number of RF chains at the same time-frequency resources. To break this Fundamental Limit, in this paper, we propose a new spectrum and energy-efficient mmWave transmission scheme that integrates the concept of non-orthogonal multiple access (NOMA) with beamspace MIMO, i.e., beamspace MIMO-NOMA. By using NOMA in beamspace MIMO systems, the number of supported users can be larger than the number of RF chains at the same time-frequency resources. In particular, the achievable sum rate of the proposed beamspace MIMO-NOMA in a typical mmWave channel model is analyzed, which shows an obvious performance gain compared with the existing beamspace MIMO. Then, a precoding scheme based on the principle of zero forcing is designed to reduce the inter-beam interferences in the beamspace MIMO-NOMA system. Furthermore, to maximize the achievable sum rate, a dynamic power allocation is proposed by solving the joint power optimization problem, which not only includes the intra-beam power optimization, but also considers the inter-beam power optimization. Finally, an iterative optimization algorithm with low complexity is developed to realize the dynamic power allocation. Simulation results show that the proposed beamspace MIMO-NOMA can achieve higher spectrum and energy efficiency compared with the existing beamspace MIMO.
Haifeng Dong - One of the best experts on this subject based on the ideXlab platform.
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spin image of an atomic vapor cell with a resolution smaller than the diffusion crosstalk free distance
Journal of Applied Physics, 2019Co-Authors: Haifeng Dong, Jingling Chen, Chen Liu, Nan Zhao, Fenzhuo GuoAbstract:The diffusion crosstalk free distance is an important parameter for spin images in atomic vapor cells and is also regarded as a Limit on the spatial resolution. However, by modulating the pumping light both spatially and temporally using a digital micromirror device, a spin image of a vapor cell has been obtained with a distinguishable stripe width of 13.7 μm, which is much smaller than the corresponding diffusion crosstalk free distance of ∼138 μm. The Fundamental Limit on the spatial resolution as determined by diffusion and the uncertainty principle is analyzed.The diffusion crosstalk free distance is an important parameter for spin images in atomic vapor cells and is also regarded as a Limit on the spatial resolution. However, by modulating the pumping light both spatially and temporally using a digital micromirror device, a spin image of a vapor cell has been obtained with a distinguishable stripe width of 13.7 μm, which is much smaller than the corresponding diffusion crosstalk free distance of ∼138 μm. The Fundamental Limit on the spatial resolution as determined by diffusion and the uncertainty principle is analyzed.
Toshiyasu Matsushima - One of the best experts on this subject based on the ideXlab platform.
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cumulant generating function of codeword lengths in variable length lossy compression allowing positive excess distortion probability
International Symposium on Information Theory, 2018Co-Authors: Shota Saito, Toshiyasu MatsushimaAbstract:This paper considers the problem of variable-length lossy source coding. The performance criteria are the excess distortion probability and the cumulant generating function of codeword lengths. We derive a non-asymptotic Fundamental Limit of the cumulant generating function of codeword lengths allowing positive excess distortion probability. It is shown that the achievability and converse bounds are characterized by the Renyi entropy-based quantity. In the proof of the achievability result, the explicit code construction is provided. Further, we investigate an asymptotic single-letter characterization of the Fundamental Limit for a stationary memoryless source. A full version of this paper is accessible at: http://arxiv.org/abs/1801.02496
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cumulant generating function of codeword lengths in variable length lossy compression allowing positive excess distortion probability
arXiv: Information Theory, 2018Co-Authors: Shota Saito, Toshiyasu MatsushimaAbstract:This paper considers the problem of variable-length lossy source coding. The performance criteria are the excess distortion probability and the cumulant generating function of codeword lengths. We derive a non-asymptotic Fundamental Limit of the cumulant generating function of codeword lengths allowing positive excess distortion probability. It is shown that the achievability and converse bounds are characterized by the R\'enyi entropy-based quantity. In the proof of the achievability result, the explicit code construction is provided. Further, we investigate an asymptotic single-letter characterization of the Fundamental Limit for a stationary memoryless source.
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Fundamental Limit and pointwise asymptotics of the bayes code for markov sources
International Symposium on Information Theory, 2015Co-Authors: Shota Saito, Nozomi Miya, Toshiyasu MatsushimaAbstract:This paper considers universal lossless variable-length source coding problem and deals with one of the Fundamental Limits and pointwise asymptotics of the Bayes code for stationary ergodic finite order Markov sources. As investigation of the Fundamental Limits, we show upper and lower bounds of the minimum rate such that the probability which exceeds it is less than ϵ ∈ (0, 1). Furthermore, we prove that the codeword length ovf the Bayes code satisfies the asymptotic normality (pointwise equation asymptotics) and the law of the iterated logarithm (pointwise equation asymptotics), where n represents length of a source sequence and “log” is the natural logarithm.
